In a May 14 letter to health-care professionals posted Tuesday to the FDA's Web site, Novartis said it received reports of kidney failure, some with a fatal outcome, in postmarketing reports of Exjade. The drug was approved in November 2005.

In a statement, Novartis said there were eight deaths associated with acute renal, or kidney, failure. More than 13,000 patients have been treated with Exjade since the drug was approved in November 2005.

Novartis said most of the patients had multiple illnesses and were in the advanced stages of their blood disorders. The company also said it received reports of patients developing a range of other blood disorders such as cytopenia, which is when the body stops producing or severely cuts back on making one or more type of blood cells, some of which led to additional patient deaths.

Although Novartis noted that patients already had preexisting blood disorders, the company said that "a contributory role for Exjade cannot be excluded."